Issue #29285: Crossbow aim is a bit off
Skyrim SE latest version, USSEP latest version, no other mods.
No matter stand or crouch, with crossbow it always shoots a bit off to the right. The nearer the target is, the obviouser this issue becomes. These are explained in the top view.
I am not sure if Bethesda intentionally designed crossbows like this. The issue matters not very much in combats, though horizontal unaccuracy is sometimes annoying.